This program focuses on age changes in dopaminergic regulation in rodent models which are pertinent to idiopathic and drug-induced basal gangliar diseases of human aging. There are three interactive projects. (I) C.E. Finch. Characertization of dopaminergic receptor age changes by biochemical and endocrinological approaches to determine early events in agining. (II) P.K. Randall. Electrophysiological and behavioral characterization of dopaminergic receptor changes during aging. (III) D.S. Linthicum and M.B. Bolger. Development of immunologic probes (anti-idiotypic antibodies with dopaminergic specificities) which will be used to characterize dopamine receptor subtypes in projects I and II.